Bad Sectors - When is a HDD a throw away

:  A question for the Experts.
I have fixed a lot on HDD's and was wondering at what point you decide just to replace the HDD because it has to many bad sectors.
For example: I am working on an what was an infected Vista computer. The HDD took quite a pounding from forced stopping (what is the proper terminology for this?). Computer freezing, being unplugged before it was shut down etc.
I have run chkdsk \r \f a couple of times but the HDD has been left with 2 bad sectors.
My question: In general or in your experience how many bad sectors would determine that you throw the hard drive out, keeping in mind that the repercussions mean buying a new HDD and installing the OS along with email database, documents, etc., etc., etc.
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mrmark75Connect With a Mentor Commented:
First check with the manufacturer to see if there is any warranty left on the drive, most manufactures have a place on their website to put in the S/N and they will tell you if it is under warranty yet. If so get a new one it will save you headache in the future. In my experience it will just come back to haunt you even if you exclude the bad sectors. With the price of hard drives $40 for a 250gb drive it's worth it not to mess with it again. To save some time with the reconstruction process you can try to copy the drive with Ghost or Acronis True Image. Depending on how bad the drive is  you may be able to copy it. I have had better luck with Acronis on flaky drives because it will keep trying to copy the sectors if it gets an error where as Ghost will kill the program. Hope that helps..  
yohanesbuleConnect With a Mentor Commented:
In my experience, user will stop using it when they are already facing bad experience a few times with the same HDD.
If you can exclude the bad sector from being written and make them unusable, then it should be fine to use the same hdd over the time, untill one needs a bigger capacity.
Gary CaseConnect With a Mentor RetiredCommented:
"... My question: In general or in your experience how many bad sectors would determine that you throw the hard drive out? "   ==>  ONE

Modern hard drives have S.M.A.R.T. logic that will automatically relocate failed sectors on the drive ... so the OS should always see ZERO.      If you get a drive that has noticeable bad sectors -- even ONE -- it's time to replace it.     Drives are so inexpensive these days it makes NO sense to use a drive that has any known issues.        

You noted in your question that replacing the drive requires "... installing the OS along with email database, documents, etc., etc., etc."   ==>   That is NOT true IF you replace the drive while it's still working.    In that case you can simply image the drive;  replace it;  and then restore the image.    In fact, you should ALWAYS have a good backup of all of your drives ... including a recent image of the OS so you can do exactly that even if the drive completely fails.    There is NO reason to ever have to reinstall the OS due to a drive failure.
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khairilConnect With a Mentor Commented:

Personally, a single bad sector makes hard disk no longer reliable. There are a few tools you can use to fix even low level format the faulty hard disk. Here is a list of tools,

Having new driver or low leveling the disk will need you to backup all your things. Backup up is painful to do, however, if nothing change in you hardware (unless you are using new hard disk - which is acceptable) you can use Norton Ghost to image the disk first and then reimage it on new disk.

Better yet, you can do disk to disk copy using Acronis ( You just lose couple of hours for backup (hopefully) and your computer is coming to normal again with new hard disk.

Good luck then.
nobusConnect With a Mentor Commented:
i always run HDD regenerator on suspect drives, it has recovered many for me !
noxchoConnect With a Mentor Global Support CoordinatorCommented:
All depends on sequence with which the new bad sectors appear. System must mark the bad sector as bad and stop trying to write data there when you run CHKDSK /r but best tool for this is HDD vendor tool. Since it fixes the bad sector (marks it as bad) OS will not see this sector anymore. But if next day or week you get more bad sectors during CHKDSK pass then replace the drive ASAP. If the bad sectors does not resurrect then it is ok to live with this drive (but do not store on it valuable data).
I have two HDDs with several bad sectors on them and they work this way for 4 years already.
ocanada_techguyConnect With a Mentor Commented:
not all drives autocorrect bad sectors.  Enterprise class and ECC correcting yes, but consumer class, it's so so.

When you think about it, it is going to depend on the nature of the bad sector(s).  A physical crash can be bad, because the heads normally float over the surface of platters thanks to Bernoulli effect and that gap is miniscule, so if the surface is scraped or scratched, the bits of crapings and filings if they jam up against the heads are like giant boulders against your car bumper, more crashing will ensue.  The surface of the platters covered with ferro-magnetic brown stuff just like what was on the ribbon of casette tapes, well, the surface will not retain the magnetic signal perfectly 100% over time, and bad sectors can happen "naturally" over time.  In fact tapes, disks, even CDs will not last forever, only decades if you're fortunate.

chkdsk does only a few retries, so it does just an ok job of finding and a LOWSY job of recovering any data off bad sectors before setting them aside, so you'd have to take note of all files/folders affected by bad sectors and recover from last good backup, or if you're wiping and redoing the disk.
The hard drive diagnostics have short and long tests, non-destructive and destructive scans, the long and destructive being more thorough respectively.  Always use the correct diagnostic, you'll get misleading untrue results trying to use wddiag on a Seagate, or seatools on a WesternDigital.

Best of all is to use SpintRite 6 (or HDDRegenerator is a Russian knockoff) but I like SpinRite for the better screen information display and logging.  It will try "heroic" measures, trying literally hundreds of times to reread data off bad sectors, uses data sampling and statistical comparison and signal strength variance analysis to retrieve/reconstruct most if not all the data at risk and remap to spare before setting aside.  Interestingly, it's also an excellent PREVENTATIVE measure, finding "iffy" spots and setting them aside before they're bad, prolonging the useful life of your drives.  Scan with it a couple times a year.
It's even possible that some bad sectors can be brought back to life, as the name HDDRegenerator implies.   It's a little like recording "black" on videotape to eliminate noise and get the best recording overtop, or degaussing a CRT.  Remember playing with ferrite filings and a magnet?  The magnetic strength can be unjumbled and made "better".
Some s.m.a.r.t settings may even be altered by the program.  Generally NO program does so, not even the manufacturer's diagnostic, as it is supposed ot be a "permanent" record of notable events and failures and manufacturers would not want anyone, experts included, able to alter and potentially facilitate making false warranty claims.

M.T.B.F. (mean time between failure) rating, expressed as hrs, is an indicator of probable useful life of a drive under normal operating conditions.  It means that on average the drive should last X hrs, your mileage may vary, you might have a lemon, or the user might abuse the drive.

Obviously if a drive is impacted or jostled while operating, that can have adverse impact on the drive.  If it is allowed to run at excessive temperatures, if the cooling fans stopped, openings clogged with dust bunnies, heat sinks detach, often a more serious issue inside crammed space of laptops or all-in-ones.

The s.m.a.r.t. monitoring is not perfect, it tries to help, think of it like the idiot lights on a car engine, there's only so much it can watch or catch, doing routine maintenance and care and having a mechanic check it are still highly useful.  The number of events within a month is an attempt at taking timeframe into account.  After all, twenty-two errors within a minute is not the same as twenty-two errors over the life of the drive.   Around 110 on a scale of 0 to 250 is normal, for some if the number goes up that's bad and for some if the number goes down that's bad.  For some of the measures the "threshold" is at 0, which essentially means there is NO threshold set, so, the BIOS will never stop during POST (power-on self-test) to say smart errors, threshold exceeded, replace drive soon, and yet the drive could nevertheless be in dire straights.
The manufacturer's diagnostic will often "know better" for the specific model what are acceptable values regardless and make better recommendations than simple s.m.a.r.t monitoring ever would.
HDTune is an excellent general tool for analysis of HDs, and it WILL say the drive should be replaced at times that s.m.a.r.t. does not.  

Obviously the actual read/write testing can too, and ESPECIALLY the SpinRite 6 (or HDDRegenerator) I reccommend.  Use it on all your drives once a year or so, give or take.

There was an EE post here asking why HDTune was warning when a smart reader did not, but I'm no longer finding it.
I did find this though
vlogg5Author Commented:
khairil That is a bad link.
Thank You everybody for the info.
vlogg5Author Commented:
People. I really screwed up on the points allocation.
This new system, that when you go to the web page to allocate points you can only view the first few lines of an answer sucks.
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